OF THE MECHANICAL EQUIVALENT OF HEAT. 
381 
Table IV., Part 1. — Experiments to ascertain the Effect of Radiation, &c. Time 
occupied by each experiment, 41 m . Weight raised for an instant, 7 730 '5 6 grains. 
No. 
Revo- 
lutions. 
Mean 
temperature 
of calori- 
meter. 
M ean 
temperature 
of air. 
Inherence. 
Rise of 
temperature 
of calori- 
meter. 
Correction 
to air 
temperature. 
Thermal effect 
of unit 
difference of j 
temperature. 
la 
lb 
9'5 
8-62 
362-355 
374-950 
358-090 
363'536 
4-265- 
11-414- 
0- 45- 
1- 10- 
Jo-684- 
0-0909 
2 a 
2 b 
10-0 
9-9 
361-090 
375-040 
363-847 
3b8*448 
2-757 + 
6-592- 
0-18 + 
0-60- 
J> 0-599 — 
0-0834 
3 a 
3b 
10-0 
10-24 
355-495 
368-430 
352-673 
357-570 
2-822- 
10'860 — 
0- 31- 
1- 02- 
J 0-683- 
0-0883 
4a 
4 b 
10-57 
10-25 
346-515 
361-985 
359-807 
365-790 
13-292 + 
3*805 + 
1-01 + 
0-15 + 
J 2-150- 
0-0906 
3a 
5 b 
9-G6 
10-74 
340-260 
354-970 
346-208 
356-487 
5-948 + 
1-517 + 
0-52 + 
0-08 + 
1 0-711 — 
0-0993 
6a 
6b 
10-82 
10-66 
357-855 
373-890 
368-538 
382-515 
10-683 + 
8 - 625 + 
1-01 + 
0-78 + 
J 1-646- 
0-1118 
Table IV., Part 2. — Experiments with almost solely Friction of Water. Weight, W, 
lifted, 7 730 ’5 6 grains. Average proportion of metallic to total friction, lame 
occupied by each experiment, 41 m . V = 0°'077214 ; P = 2'77386. 
No. 
Number of 
revolutions. 
R + r. 
Capacity 
of the 
calorimeter. 
C. 
Mean 
temperature 
of the 
calorimeter. 
Mean 
temperature 
of 
the air. 
Difference. 
Rise of 
temperature 
or the 
calorimeter. 
Diito, 
corrected 
for 
radiation, &c. 
T. 
Mechanical 
equivalent 
or 
R W P 
C T V 
3336 -66 
3344-2 
3343 -42 
3341 -23 
3330 75 
3335 -33 
83363 -7 
83944-7 
83959 7 
83949 -7 
83975 0 
83965 -0 
369-487 
369 -065 
362 -809 
355-191 
348-411 
366 -732 
361 -043 
366 -560 
354 -425 
362 -160 
350 362 
375 533 
8-444- 
2 -505- 
8 384- 
6 969 + 
1 -951 + 
8 801 + 
13 495 
14-078 
13 -646 
14 -927 
14 -416 
15 040 
14-325 
14-337 
14 447 
14-490 
14-293 
14 -240 
768 32 
769 '39 
763 18 
760 -44 
768 -30 
772-19 
Average 
361 -949 
or 58° -14 
\ - 
•• 
•• 
•• 
766 97 
It will be obvious that, in the experiments of the above Table, where the heat 
evolved was able to raise the temperature of the calorimeter little more than 1°, great 
accuracy could not be expected without taking the average of a very large number of 
observations. In fact, the degree of accuracy will increase nearly with the square of 
the rise ol temperature per unit of time/" and the square root of the number of 
observations. 
I.e., supposing the “Differences, ’ for calculating the air correction, increase with the values of T. 
